package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"

	again "git.rootprojects.org/root/go-again"
	"git.rootprojects.org/root/go-again/data/jsondb"
)

func main() {
	portEnv := os.Getenv("PORT")
	dbEnv := os.Getenv("DATABASE_URL")

	portInt := flag.Int("port", 0, "port on which to serve http")
	addr := flag.String("addr", "", "address on which to serve http")
	dburl := flag.String("database-url", "", "For example: json://relative-path/db.json or json:///absolute-path/db.json")
	flag.Parse()

	if "" != portEnv {
		if 0 != *portInt {
			log.Fatal("You may set PORT or --port, but not both.")
			return
		}
		n, err := strconv.Atoi(portEnv)
		if nil != err {
			log.Fatalf("Could not parse PORT=%q.", n)
			return
		}
		*portInt = n
	}
	if *portInt < 1024 || *portInt > 65535 {
		log.Fatalf("`port` should be between 1024 and 65535, not %d.", *portInt)
		return
	}
	portEnv = strconv.Itoa(*portInt)

	if "" != dbEnv {
		if "" != *dburl {
			log.Fatal("You may set DATABASE_URL or --database-url, but not both.")
			return
		}
		*dburl = dbEnv
		// TODO parse string?
		// TODO have each connector try in sequence by registering with build tags like go-migrate does?
	}
	if "" == *dburl {
		log.Fatalf("`database-url` must be specified." +
			" Something like --database-url='json:///var/go-again/db.json' should do nicely.")
		return
	}

	db, err := jsondb.Connect(*dburl)
	if nil != err {
		log.Fatalf("Could not connect to database %q: %s", *dburl, err)
		return
	}

	s := &scheduler{
		DB: db,
	}
	mux := http.NewServeMux()
	server := &http.Server{
		Addr:           fmt.Sprintf("%s:%s", *addr, portEnv),
		Handler:        mux,
		ReadTimeout:    10 * time.Second,
		WriteTimeout:   10 * time.Second,
		MaxHeaderBytes: 1 << 20,
	}
	//mux.Handle("/api/", http.HandlerFunc(handleFunc))
	mux.HandleFunc("/api/v0/schedules", s.Handle)
	mux.HandleFunc("/api/v0/schedules/", s.Handle)

	// TODO Filebox FS
	mux.Handle("/", http.FileServer(http.Dir("./public")))

	fmt.Println("Listening on", server.Addr)
	log.Fatal(server.ListenAndServe())
}

type ScheduleDB interface {
	List(string) ([]*again.Schedule, error)
	Set(again.Schedule) (*again.Schedule, error)
	Delete(accessID string, id string) (*again.Schedule, error)
}

type scheduler struct {
	DB ScheduleDB
}

func (s *scheduler) Handle(w http.ResponseWriter, r *http.Request) {
	// note: no go-routines reading body in handlers to follow
	defer r.Body.Close()

	token := strings.TrimPrefix(r.Header.Get("Authorization"), "Bearer ")
	if 32 != len(token) {
		http.Error(w, "Authorization Header did not contain a valid token", http.StatusForbidden)
		return
	}
	ctx := r.Context()
	ctx = context.WithValue(ctx, "token", token)
	r = r.WithContext(ctx)

	switch r.Method {
	case http.MethodGet:
		s.List(w, r)
		return
	case http.MethodPost:
		s.Create(w, r)
		return
	case http.MethodDelete:
		s.Delete(w, r)
		return
	default:
		http.Error(w, "Not Implemented", http.StatusNotImplemented)
		return
	}
}

func (s *scheduler) List(w http.ResponseWriter, r *http.Request) {
	accessID := r.Context().Value("token").(string)
	schedules, err := s.DB.List(accessID)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	buf, err := json.Marshal(schedules)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Write(buf)
}

func (s *scheduler) Create(w http.ResponseWriter, r *http.Request) {
	// TODO validate user
	accessID := r.Context().Value("token").(string)

	/*
		br, bw := io.Pipe()
		b := io.TeeReader(r.Body, bw)
		go func() {
			x, _ := ioutil.ReadAll(b)
			fmt.Println("[debug] http body", string(x))
			bw.Close()
		}()
		decoder := json.NewDecoder(br)
	*/
	decoder := json.NewDecoder(r.Body)
	sched := &again.Schedule{}
	err := decoder.Decode(sched)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	fmt.Printf("New Schedule:\n%#v\n", sched)

	// TODO validate and modify
	sched.AccessID = accessID
	sched2, err := s.DB.Set(*sched)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	buf, err := json.Marshal(sched2)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Write(buf)
}

func (s *scheduler) Delete(w http.ResponseWriter, r *http.Request) {
	// TODO validate user
	accessID := r.Context().Value("token").(string)
	parts := strings.Split(r.URL.Path, "/")

	// ""/"api"/"v0"/"schedules"/":id"
	if 5 != len(parts) {
		http.Error(w, "Not Found", http.StatusNotFound)
		return
	}

	id := parts[4]
	sched2, err := s.DB.Delete(accessID, id)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	buf, err := json.Marshal(sched2)
	if nil != err {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Write(buf)
}